Rotary regenerative heat exchanger with shutters



R. RIGBY April 5, 1955 ROTARY REGENERATIVE HEAT EXCHANGER WITH SHUTTERSFiled April 22, 1952 4 Shets-Sheet 1 i a an n m B 3 K B 2 m 3 a n n 3 42 M 2 7m n 3 l (I l F a m A A 1 i 5 m m m n w.

n a H mm 9 a M n u 4 a s x w 0 5 3 INVENTOK RKZHARD RlSSBY HIS ATTORNEYFig.8

April 5, 1955 R. RIGBY 2,705,615 ROTARY REGENERATIVE HEAT EXCHANGERWITHSHUTTERS Filed April 22, 1952 4 Sheets-Sheet 2 mcHARD RKaBY BY: fl

HIS ATTORNEY April 5, 1955 R. RIGBY 2,705,615

ROTARY REGENERATIVE HEAT EXCHANGER WITH SHUTTERS Filed April 22, 1952 4Sheet-Sheet 5 INV ENT'OK RlC HARD R I GBY Hi5 ATTO EN EN R. RIGBY April5, 1955 ROTARY REGENERATIVE HEAT EXCHANGER WITH SHUTTERS Filed April 22,1952 4 Sheets-Sheet 4 Ila Fig.9

INVENTOR v. Y mm a RW mT M/ WW5 R H United States ROTARY REGENERATIVEHEAT EXCHANGER WITH SHUTTERS Richard Rigby, Great Crosby, Liverpool,England, as-

signor to Shell Development Company, Emeryville, Calif., a corporationof Delaware This invention relates to a regenerative heat exchanger ofthe kind in which the heat-accumulating packing is contained in orconstituted by a matrix consisting of a plurality of separate,longitudinal matrix ducts arranged in a matrix drum, usually parallel toone another, the ends of the ducts forming end contact faces which areswept by ring-shaped shutters mounted in fluid-sealing contact withthese end faces and rotatable about the common axis of the shutters,which axis is offset from that of the drum, the interiors of theshutters being in constant communication with end ports of first orinner conduits for the flow of one of the heat-exchanging fluids andtheir exteriors being in constant communication with second or outerconduits for the flow of the other heatexchanging fluid. Sweeping of theend faces of the matrix is effected by relative motion between thematrix drum and the shutters about the central axis of the drum, eitherby rotating the drum while keeping the said common axis of the shuttersfixed or by keeping the drum stationary and moving the said common axisof the shutters and the termini of the first or inner conduits along aclosed path, e. g., a circular path, about the central axis of the drumwhereby the shutters sweep both faces with coordinated movements. Suchheat exchangers, which are hereinafter referred to as regenerative heatexchangers of the kind specified, are described, for example, in my U.S. Patent No. 2,578,945.

As applied, for example, for use in gas turbine plants, the hot exhaustgas from the turbine is caused to flow through the outer conduits andthrough the ducts of the matrix the termini of which are, for themoment, outside t e area enclosed by the shutters and the coldcompressed working medium is caused to flow through the inner conduitsand through the matrix ducts that then have their termini inside theshutter areas. The hot and cold heat-exchanging media are often at ahigh pressure difference, and the rotatability of the shutters on theirown axis is intended to enable them to form and maintain a matingrelationship between themselves and the drum faces such as will insure aseal which can stand up to the pressure differences involved.

As illustrated for example in Figures 1-5 and 8 of my aforesaid patent,in such regenerative heat exchangers the matrix drum may be stationaryand'the eccentric shutter supports (e. g., eccentric spindles driven bya crank or supported'within the ports of crank-shaped rotatable innerducts) may be swept in unison over the two and contact faces of thematrix drum in such a manner that the common axis of the shutters movesin a closed path, such as a circular path, surrounding the central axisof the matrix drum at a suitable angular sweep velocity, the shuttersbeing mounted for rota tion about their common, eccentric axisseparately from the said angular sweeping motion; or, as illustrated inFigure '7 of the said patent, the central of the matrix drum and theposition of the shutter supports mayboth be kept stationary and both thedrum and shutters may be rotated about their respective axes, therotation of the drum thereby producing the relative sweeping motion andthe angular speed of the drum being the angular sweep velocity which isseparate from and differs from the angular velocity of the shutters, sothat there is again a relative rotation between the drum and theshutters. in the former case rotation of the shutter rings relative tothe drum about their own common axis, which is essential to insure evenwear so as to form and maintain a mating relationship with the matrixdrum and it tent .M

7 2,705,615 Patented Apr. 5, 1955 2 to insure iluid-scaling contactbetween the shutter and the matrix face, is induced by the frictionalforces exerted by the shutter and matrix faces during the sweeping,

motion, the latter being induced positively by rotating the shuttersupports, In the latter case, a similar relative sweeping motion occurswhich may be induced in either of two ways: the matrix drum may berotated by a suitable power drive and the shutters may be induced torotate about their own axis by frictional contact with the faces of thepositively driven matrix drum; or, one or both of the shutters may berotated about their axis by the power drive and the matrix drum may beinduced to rotate at a different speed by frictional forces between theshutter or shutters and the drum. T he instant invention is applicableto both of these cases, which have in common the circumstance that theshutters rotate about their own axis at angular shutter velocities thatare separate from the angular sweep velocity (in the sense that they arenot constrained by drive elements to rotate at any set ratio of angularvelocities) but are yet related by the frictional drag occurring betweenthem.

While for simplicity in description reference is made herein to a commonaxis of the ring-shaped shutters, it should be understood that this isstrictly correct only in the usual case, to be illustrated, wherein theend con: tact faces of the matrix drum are both perpendicular to thedrum axis and the matrix ducts run parallel to the drum axis; it will beappreciated that the invention may be applied to other, equivalentarrangements of the matrix drum, wherein the end faces are notnecessarily perpendicular to the drum axis or the matrix ducts are notnecessarily parallel to the drum axis, and that suitable modificationsin the geometry will occur to those skilled in the art to satisfy therequirement that the two shutters rotate in the planes of theirrespective end con tact faces and that the two shutters at. all timessurround the termini of the same variable group of matrix. Further, theinvention is not limited to constructions employing only one shutter ateach end or" the matrix drum.

Gwing to the wear on the shutters and/or on the end contact faces of thematrix drum which occurs in normal use, the intimacy of contact of thering-shaped shutters on the contact faces and, hence, the efliciency ofthe fluid seal, is liable to diminish. For the same reason the ratio ofthe angular shutter velocities to the angular sweep velocity is liableto vary. Thus, when the shutters are positively driven, the ratio of theangular shutter velocity to the rotational speed of the matrix (equal tothe sweep velocity when the positions of the shutter supports arestationary) will tend to increase with wear while, when the matrix drumis positively driven, the same ratio of angular velocities will tend todiminish with wear. r

In this specification and claims, the ratio of the posi tively inducedangular velocity to the frictionally induced angular velocity. isdesignated the induced velocity ratio. Thus, when the drum is stationaryand the supports for the shutters are swept about the drum axis bypositive drive, the designated ratio is the ratio of the angular sweepvelocity to the angular shutter velocity; this is true also when arotary matrix drum is positively rotated and the shutter supports remainstationary. However, when the shutters are positively rotated abouttheir common axis and the drum is induced to rotate by frictionalcontact with the shutters, the designated ratio is the ratio of theangular shutter velocity to the angular sweep velocity.

Both the leakage of heat-exchanging fluid between. the

shutters and the matrix drum contact faces, and the induced velocityratio, are functions of the pressure exerted by the shutters on thematrix contact faces Underlying the present invention is thecircumstance that these functions are so related that at inducedvelocity ratios below a more or less well-defined. critical value, theleakage is small and does not vary greatly with the said inducedvelocity ratio, while above this critical induced velocity ratio, theleakage tends to increase rapidly with increasing ratios. As thefrictional force exerted by the shutters on the matrix drum is equal andopposite to that exerted by the matrix drum on the shutters, similarcritical velocity ratios exist in the two cases mentioned above, viz.,using shutters that are freely rotatable and driven frictionally from apositively driven matrix drum or by a positive sweeping motion of theirsupports over a stationary drum on the one hand, or using a freelyrotatable matrix drum that'is driven frictionally by shutter rings thatare positively driven on the other hand. Similar ratios exist also forthe hybrid case wherein only one of the shutters is positively drivenand the matrix drum is induced to rotate by frictional contact of onecontact face thereof with the shutter, the other shutter being, in turn,driven rotationally by frictional contact with the other face of thematrix drum. In consequence, it is found that the foregoing relationshipinvolving a critical induced velocity ratio applies irrespective of themeans employed for generating the sweep and shutter velocities.

According to the main feature of the present invention, in aregenerative heat exchanger of the kind specified the pressure betweenthe matrix drum and the shutter is controlled so as to effect the properfluid seal without imposing so great a pressure as to cause excessivefriction and wear, by providing a variable pressure device. In thepreferred embodiment this is effected by positively driving some partsof the exchanger, less than all, rotationally so as to induce positivelyeither the angular sweep movement or the angular shutter movement;inducing rotation to a member not positively driven by friction betweenat least one shutter and the end contact faces of the matrix drumcontiguous thereto; sensing the induced velocity ratio; and varying thepressure between the shutters and the contact faces of the drum inaccordance with the sensed induced velocity ratio. The sensing isconveniently effected by providing a sensing device responsive to therelative magnitudes of the angular sweep velocity and the angularshutter velocity and connecting it to control the variable pressuredevice to increase the said pressure if the induced Velocity ratio risesabove a predetermined value and, preferably, to decrease the saidpressure upon a decrease in the said ratio. Such an increase in pressureincreases the intimacy of contact to perform the double function ofrestoring (i. e., decreasing) the induced speed ratio and reducing therate of leakage. If the said predetermined value of the induced velocityratio is the same, or substantially the same as the aforesaid criticalvalue, the leakage is maintained at the low value associated withinduced velocity ratios below the critical value.

While it is not essential for the purpose of maintaining the sealingcontact and mating relationship, that the pressure be reduced when theinduced velocity ratio is less than the critical value, it isadvantageous to provide a variable pressure device that can act in thissense also. In this way the wear of the contact faces, and also thepower required to drive the positively-driven member, are reduced to aminimum. Moreover, in the case of a regenerative heat exchanger whereinthe shutters are positively driven, a reduction in the induced velocityratio, i. e., a rise in the angular sweep velocity of the drum beyond adesignated value may impair the heat transfer efficiency; this may beprevented by this arrangement.

The pressure of the shutters on the contact faces of the matrix drum maybe exerted, for example, by a spring or a pneumatic or hydraulic device,the last of these being generally the most convenient. The means forsensing the induced velocity ratio and controlling this pressure inaccordance with the invention may comprise a differential gear in whichone Wheel is driven by the matrix drum or by the supports that cause theshutters to sweep the matrix drum and another wheel is driven by therotation of the shutters about their axis, so as to form a differentialspeed-responsive mechanism adapted to actuate a device of known kind forcontrolling the loading of the spring or the pneumatic or hydraulicpressure, as the case may be. The differential gear is sensitive to anychange of speed of one wheel relative to the other and the resultingreaction may be transmitted to the variable pressure control device byany suitable means, for example, mechanical, electrical, pneumatic orhydraulic. Where such a mechanism is used in the present invention, thespeed setting will preferably be the aforesaid critical induced velocityratio. In one particular model which was subjected to test, thiscritical induced velocity ratio was about 4:5, but the invention mayobviously be applied to heat exchangers wherein ratios are maintained.

If the matrix drum is the positively-driven member, it will generally benecessary to locate the drive at the periphery of the matrix drum.Where, as is usually the case, this location is at a comparatively hightemperature, it is preferred to provide a positive drive for theshutters. For this purpose, and also for the purpose of applyingpressure on the shutters, each of the shuttersmay be provided with ashaft extending from the hub of the shutter through an opening in a bendor elbow in the duct for the heat-exchanging fluid communicating withthe in teriors of the shutters.

Whichever member or members is or are not positively driven is or aremounted so as to be freely rotatablezwith a minimum of friction otherthan the friction between the shutters and the end contact faces of thematrix. Gwing to the difiiculty of providing low-friction bearings forthe support rollers at the periphery of the drum, where this is thenon-positively rotated member, bearings at this lo cation may themselvesbe mounted so as to be frictionally driven at a speed corresponding withthe desired angular velocity of the drum or sweep velocity.

According to a further feature of the invention in a regenerative heatexchanger of the kind specified wherein the axes of the shutters sweepabout the central axis of stationary matrix drum, means actuated independence upon the angular sweep velocity are provided for con trollingthe pressure between the shutters and the respective matrix drum facesso as to increase the said pressure if the said speed rises above apredetermined value.

The invention will now be described in more detail by reference to theaccompanying drawings forming a part of this specification andillustrating certain preferred embodiments of the invention, wherein:

Figure l is a longitudinal sectional view of a regenerative heatexchanger taken on a horizontal section plan indicated by the line II ofFigure 2, certain auxiliary equipment being shown diagrammatically;

Figure 2 is a transverse sectional view taken on the broken line IIII ofFigure l;

Figure 3 is an enlarged sectional plan view showing the differentialgearing coupled to the rotating shutters and the drum;

Figure 4 is a sectional view taken on the line '[V-lV of Figure 3 but ona reduced scale;

Figure 5 is a longitudinal sectional view of a valve mechanism forming apart of the hydraulically operated servo-system shown in Figures 1 and4;

Figure 6 is a fragmentary transvers'e'sectional view of a heat exchangertaken on a vertical section plane showing a modified arrangement forcoupling the differential gearing to the rotatable matrix drum;

Figure 7 is a horizontal sectional view taken on the line VIIVII ofFigure 6;

Figure 8 is a fragmentary plan section showing a modified drivearrangement for the rotatable matrix drum;

Figure 9 is a plan view of a modified embodiment showing a springarrangement for loading the shutters; and

Figure 10 is a fragmentary longitudinal sectional view of a regenerativeheat exchanger according to the invention wherein the matrix drum isstationary.

Referring first to Figures'l and 2 of the drawings, the heat exchangercomprises a cylindrical or drum-shaped casing 10 of a circular crosssection in which is mounted a matrix 11 consisting of a honey-comb ofseparate, parallel ducts 11a which extend longitudinally parallel to thecentral axis of the drum and which are in thisembodiment, arranged tofill the entire cross-sectional area of the drum. These ducts terminatein plane end contact faces and may have any desired cross-sectionalshape, e. g., square as shown in Figure 2 or as shown in my aforesaid U.S. Patent No. 2,578,945. Each duct may contain a packing (not shown) ofheat-accumulating material, for example, wire gauze, wire wool or thelike. One specific arrangement of such heat accumulating material isdisclosed in the copending application of Tipler,

Serial No. 209,037, filed February 2, 1951 and now Patent.

The casing thus forms a pair of outer conduits com-- other inducedvelocity municating with the termini of certain of the ducts 11a. Thedrum may be mounted on support rollers 16 and an annular gear rack 17 isfixed to the drum for rotation therewith. Fixed within the casingsections 13 and 14, e. g., cast integrally therewith, and situatedsubstantially tangentially to the interior walls, are cyclindrical innershutter conduits 18 and 19 having circular cross sections and a diameterequal to about half that of the outer casing. The shutter conduits havetheir ports adjacent the end faces of the drum 10, said ports beingsituated eccentrically to the central axis of the drum and extendingover only minor parts of the areas of said end faces. The ports of theshutter conduits are of equal size and are in alignment to surround thetermini of the same variable partial group of matrix ducts; they formshutter supports for the shutters 29, described below. When the drum isrotated there results a relative sweeping rotary motion between the drumand the shutter supports and different matrix ducts are included in thesaid partial group. The shutter conduits 18 and 19 communicate withpipes 21 and 21a, respectively, for the'flow of a second heatexchangingfluid.

In use, one of the heat-exchanging fluids is caused to flow throughouter conduits or casing sections as indicated by the arrow A and theother fluid is passed through shutter conduits 13 and 19, preferably incounter-current as indicated by the arrow B. The regenerator isparticularly useful for use in gas turbine plants, in which case thefluid flowing through outer conduits is the hot exhaust gas from theturbine, while that flowing through inner shutter conduits is the coolair flowing from the compressor to the combustion chamber. It will beappreciated that the air is in such a case at a much higher pressurethan the gas, and that it is therefore of importance to provide anadequate seal between the rotating matrix and the stationary conduits 18and 19. For this purpose, as described in the aforesaid patent, aringshaped shutter 29 is mounted within each of the shutter conduits.Each shutter has a flat, annular sealing face that bears on one of theplane end contact faces of the matrix drum and is of suflicient width tospan the full cross-section of the end of one duct 11a. Each shutter isfixed on a supporting frame forming the shutter support proper andhaving an annular back-up ring 22 that is axially and rotationallymovable within the respective shutter conduit and is externally influid-tight relation to the shutter conduit. The shutters 20 are therebyposi tioncd within the shutter conduits but may likewise be movedaxially and rotated about their common axis. Each supporting frame hasspokes 23 connecting the back-up ring to a central hub which is securedto a rotatable and axially movable shutter shaft 25 or 250 that extendsout of the casing through a fluid-tight seal in housing 26'. Theconnections between the hub and shafts transmit axial thrust and torqueabout the common axis of the shafts but is loose enough to permit aslight tilting. or canting of the supporting frame, which enables theshutters 20 to rock with respect to the shafts with any wear ordisturbance between the shutter faces and the contact faces of thematrix drum. The periphery of the drum it may be sealed to the casing 12to prevent bypassing of gas, e. g., by running seals- The shutter rings20 are forced into contact with the matrix faces by the differentialpressure between the heat-exchanging fluids when the pressure in theshutter conduit exceeds that in the outer part of the casing; however,the invention is not limited to such a relation between the pressures ofthe heat-exchanging fluids because positive means are provided, asdescribed below, for urging the shutters against the matrix drum. It isevident that rotation of the shutter shafts 25 and 25a and the shutters2%) causes a relative rotary motion between the shutters and the matrixdrum as the latter is rotated about its own axis; this causes theshutters to grind in on the matrix faces and a mating relationshipbetween the surfaces of the rin s and the matrix drum is formed andmaintained. This grinding and sealing action is facilitated by theaforesaid loose connection between the shafts and shutter supportframes, which facilitates the mating of the said surfaces and therebypromotes the maximum avoidance of leakage of fluid medium from theshutter ducts to the space served by the outer part of the casing 12-14.

Suitable means are provided for rotating the coaxial shutter shafts 25,25a at a common speed; this may, for example, include a pair ofsprockets 26, 26a on a common drive shaft 27 connected by sprocketchains 28, 28a to sprockets 29, 29a, respectively, on the shuttershafts. It may be noted that only a limited axial movement of theshutter shafts, too small to interfere with the proper operation of thesprocket drives, occurs in the operation of the heat exchanger. Frictionof the shutters 20 on the contact faces of the matrix drum causes thelatter to be rotated when the drive shaft 27 is turned. The ratio of thepositively induced angular velocity of the shutter rings 20 to thefrictionally induced angular velocity of the matrix drum 10 is, in thisembodiment, the induced velocity ratio, as heretofore defined.

The shutters are urged against the matrix contact faces by stationaryhydraulic loading cylinders 39, 39a, which contain pistons 31, 31a,connected to the shutter shafts. A suitable pressure fiuid, e. g., oil,is admitted into the cylinders by branch conduits 32, 32a, both of whichare in communication with a pressure regulating valve 33 and with asource of fluid under pressure, such as a reservoir, indicatedschematically at 34, and a pump 35. A return conduit 36 permits fluid tobe vented to the reservoir. The cylinders and pistons thus constitutevariable pressure devices for applying to the shutters pressures thatare controlled by the regulating valve 33 which is, in turn, actuated bya sensing device.

The means for sensing the induced velocity ratio comprises adifferential gear unit 3'7 illustrated in Figures 1 and 3. This unit issupported on stationary bearings 38 by means of its rotatable inputshafts 39' and 47. Input shaft 39 is coupled to the shutter shaft 25a bymeans of sprockets 4t and ll and a sprocket chain 42. The gear unitcomprises a casing 43 which is rotatable about the shaft 39 and hastubular extension 43:: extending over a part of this shaft. For assemblythe casing may be made of two sections, as shown. The casing constitutesthe planet carrier and supports the shafts 44 and 44a of planet gears 45and 45a, and houses a sun wheel 46 which is mounted fast on a shaft 47,is rotatable therewith within the casing, and meshes with the gears 45,45a. Also rotatable within the casing is an internally toothed gear 4dmeshing with the planet gears and fast on the shaft 39. The shaft 47forms the second input shaft to the differential gear unit and iscoupled to the matrix drum 10 by means of a pinion 49 meshing with thegear. rack 17 and contained within an enlargement 12a of the casing. Itis evident that the internally toothed gear wheel 48 is driven in onedirection at a velocity proportional to that of the shutters 20 whilethe sun wheel 46 is driven in the opposite direction at a velocityproportional to that of the matrix drum, and that the casing 43 willremain stationary at a predetermined ratio of these velocities, which isdetermined by the gear ratios of the coupling devices. When the inducedvelocity ratio varies from the said predetermined value the casing 43 iscaused to rotate in a direction dependent upon the direction of thedeviation. This rotation produces a torque for controlling theregulating valve 33.

Referring to Figures 3 and 4, a lever Si is integral with the sleeve 51which is rotatably mounted on the casing 43; it bears frictionallyagainst a shoulder of the casing at one end of the sleeve and against aspring 52 at the other end thereof. The spring is retained by a nut 53threaded to a tubular extension 43:: of the casing. The spring 52 isloaded sufficiently to secure the transmission of torque from the casing43 to the lever when the former rotates while permitting slippage. Thistorque may be in a clockwise or counter-clockwise direction and may varyfrom zero upwards according as the induced velocity ratio is greaterthan or less than the said predetermined value. The lever 50 is linkedby a pivoted connecting rod 54 to a combined. cam and lever 55 which ispivoted at 56 and operates the pressure regulating valve 33 which may beof a known type.

The balanced pressure regulating and relief valve illustrated in Figure5 comprises a housing 557 having a longitudinal bore providing apressure inlet passage 58 for connection to the pump 35 and a passage 59for connection to the branched conduits 32, and 32a, the passages 58 and59 being always in communication. The housing has a vertical boreintersecting the former and providing an exhaust passage 60 forconnection to the return conduit 36 and a chamber 61 within which theexhaust valve member 62 is slidably mounted. The top of this bore isclosed by a head 63 having a bore 64 for receiving the reduced, upperpart of the valve member 62. The valve member is formed as a piston, theunder side of which is equal in area to the upper side. The two sides ofthe piston are interconnected by an orifice 65, and the upper side is incommunication with the exhaust passage 60 via a bore 65a in the headcontrolled by a pilot ball valve 66 and a bore 67 extending through thevalve member. A light spring 68 holds the exhaust valve member on itsseat 69 and this valve will remain closed by the action of the spring aslong as the pilot valve 66 is closed, the fluid pressure being equal onboth sides of the piston. If the pressure in the control pressurepassages 58 and 59 rises above the Pilot valve seating, the latter willopen and permit oil to bypass to the exhaust passage 69. This will crete a ifferenti l pre sur across the piston, due to a Pressure dr p inthe orifice 65 and cause the piston and exhaust valve to rise and thusrelease oil to the return conduit 36, thereby partly venting thecylinders and 3011. When the pressure falls the valve 66 closes and theSpring 68 closes the valve member 62. The pressure in the passage 59 istherefore dependent on the loading of the pilot ball valve 66. Thisloading is controlled by varying the amount of compression on a spring70 via a piston 71 connected to a cam follower 72 in engagement with thecam 55'. It will be understood that the valve 62 does not extend fullyacross the longitudinal bore in the housing 63 and therefore permitsfull 7 communication between passages 58 and 59 in all posi tionsthereof. The pump is operated at a low pumping rate and oil iscontinually supplied to the passage 58.

In operation the positively driven shutter rings 20 induce rotation ofthe matrix drum 10 through friction of their sealing faces. The shuttershaft 25a thereupon drives the input shaft 39 and the internally toothedgear wheel 48 while the frictionally-induced rotation of the drum istransmitted to the sun wheel 46 via the spur gear 49. The gear wheelsizes are so chosen in diameter in relation to each other as to securethe result that when the induced velocity ratio is about equal to thecritical value above which leakage across the mating surfaces of theshutters and end contact faces of the matrix drum tends to increase,there is no torque transmitted to the planet carriercasing 43 and,hence, to the lever 50. When, however, this induced velocity ratioincreases (indicating too much slippage between the shutter and r drum),a torque is induced to the lever which thereupon actuates the cam toshift the piston 71 to the right and thereby increases the loading ofthe spring 70 on the pilot ball valve 66. This increases the fluidpressure in. the cylinders 30 and 30a and thereby increases the axialthrust which is applied to the shafts 25 and 25a and'increases thehydraulic loading on the shutters, whereby the induced velocity ratio isrestored to the desired value and leakage of heat-exchanging fluid isminimized or eliminated. If the induced velocity ratio should fall belowthe said critical value, a torque in the opposite direction is inducedto the lever 50 and the hydraulic servo-mechanism is actuated in theopposite sense to reduce the hydraulic loading on the shutters so as toincrease the said induced velocity ratio.

It will be evident that the arrangement described above by reference toFigures 1 to 5 could equally well apply to the case in which the matrixdrum 10 is positively driven and induces rotation to the shutters 20 byfriction. Such a. modification is indicated in Figure 8 wherein theshaft 47a, new larger than the shaft 47 of Figure 1, carries a sprocket73 meshing with a sprocket chain 74, the latter being driven by anysuitable power device. The shaft 47a thereby rotates the matrix drum 10through the pinion 49 and annular gear rack 17. The parts 26 to 29,inclusive, of Figure 1 would, of course, be omitted in this embodiment.

Referring to Figures 6 .and 7 there is shown an alternative arrangementfor driving the differential gear unit off the periphery of the matrixdrum involving a friction roller. In this embodiment, the input shaft 47of the differential gear unit is bearin gly supported in a gear casing75 which is fixed to the casing 12 outside of the periphery ofthematr'ix drum and carries fixed thereto a gear wheel 76 situatedbetween the parallel, spaced P r s of a pi lo er arm 7 which so c rriegear wheels'78 and 79. Mounted on the shaft carrying the gear wheel 79is a friction roller 80 which is urged into contact with the peripheryof the matrix drum 10 through a spring 81 housed within a well 82 of thecasing 75 and pressing against the follower arm '77 through an axiallymovable abutment pin 83. The follower arm is rotatable about the shaft47. Thereby rotation of the drum 10 is transmitted via the frictionroller 80, gear wheels 79, 78 and 77 to the shaft 47 and to the sunwheel 46 mounted thereon, The pivotal support of the follower arm 77about the shaft 4'! permits rocking of the arm around the shaft insympathy with any irregularities in the peripheral surface of the matrixdrum.

As was indicated above, the invention is not limited to the use ofhydraulic devices for loading the shutters and other arrangements, suchas springeloaded devices, may be used. Such an arrangement isillustrated in Figure 9, wherein like reference numbers indicate partspreviously described. The rotatable and axially movable shafts 25 and25a carry thrust collars 84 forming rotatable abutments for coiledsprings 85 that bear against the rotatable races of thrust bearingshaving their nonrotatable races mounted within sleeves 8.6. Thesesleeves are rigidly connected to arms 87, 8.7:: that are in turn rigidlyconnected to coaxial rods 88 and 88a, respectively, which are axiallyslidable in stationary suPPQrts .89. The parts of the rods engaged bythe supports have flattened sides, as shown, whereby the rods aresecured against rotation. The near ends of the rods are internallythreaded with left.- and right-hand threads, respectively, and receive astud 90, the ends of which are correspondingly threaded. The studcarries a sprocket 91 which is connected by a sprocket chain 92 to asprocket 93 fixed on the sleeve 51 (see Figure 3) of the differentialgear unit. This latter sprocket thus replaces the lever 50 of theprevious embodiment and rotation of the casing 43 of the differentialgear imparts a torque to the sprocket 93.

It is evident that when the induced velocity ratio rises thedifferential gear unit 37 imparts a torque to the sprocket 93 to rotatethe stud 99 in a direction pulling the rods 88 and 88a closer together.This translatory motion is transmitted to the sleeves 86 whereby thesprings 85 are compressed and an increased axial force is imposed on theshafts '25 and 25a to increase the loading on the shutters and reducethe induced velocity ratio. Since the assembly of the two rods 88, 88aand the stud is free to shift as a unit, it assumes a positiondetermined by the springs 85 such that these springs are equally loaded.The pressures of the shutters 20 on the opposite end contact faces ofthe matrix drum will, therefore, be substantially equal regardless ofthe angular position of the stud 90. A variation in the induced velocityratio in the downward direction similarly results in a torque beingapplied to the sprocket 93 but in the opposite direction, whereby thespring tensions are reduced and the loading on the shutters is reduced.

In the special case where the matrix drum is stationary and all that isneeded is a control .of the relation between the velocity of rotation ofthe shutter axis about the of the drum to the angular velocity of theshutters themselves with respect to the drum, it will be evident thatthe arrangement for controlling the pressure between the shutter and therespective matrix drum contact. faces with a view to maintaining theinduced velocity ratio within the desired limits will undergo somemodification over that described above. One such arrangement is shown inFigure 10 by way of illustration. This view shows a portion of the heatexchanger according to Figure 8 of the aforesaid U. S. patent, whereinthe matrix drum is stationary and comprises concentric outer and innercylindrical shells and 110a, the latter enclosing an inner dead spaceand the annular space between these shells containing the matrix ducts111 which terminate in annular, plane contact faces; only one of thesefaces appears in the drawing, it being understood that the opposite faceis similarly arranged. A stationary outer duct 112 for the flow of oneheat-exchanging fluid is fixed to each end of the shell 110, shaped sothat the ends remote to the matrix drum curve away from the central axisof the drum. An inner duct 113 for the flow of the o he h st xshang ngmedium, 2-, e one a th hi h r pressure, is mounted coaxially with theaxis of the shell 110 and within each outer conduit 112, terminatingsome distance from the contact face of the matrix drum. A rotatable,crank-like duct 114 is fitted to each inner conduit 113 and rotatablysealed thereto by means of sealing flanges 115, 116. The inner ends ofeach duct 114 extend laterally outwardly from the central axis of thedrum and terminate in close proximity to the drum, the ports thereofbeing substantially internally tangent to the shell 110 and externallytangent to the shell 110a. Each inner end has an annular ring 117 withan external row of gear teeth 118 which mesh with a spur gear 119. Byturning the spur gear 119 the ring 117 and duct 114 may be rotated aboutthe central axis of the matrix drum, it being understood that the twoducts at the opposite ends of the drum are moved in synchronism. Theport of the duct 114 is enlarged near the matrix drum and contains aring-shaped shutter 120 which has limited axial movement and isrotatable within the port, being externally in fluid-tight relation tothe port and having an annular sealing face in rubbing contact with thematrix contact face. The shutter has radial spokes 121 extending to acentral hub 122 to which a shutter shaft 125 is connected loosely topermit the shutter to rock or tilt with respect to the shaft axis, butto transmit torque and axial thrust. The shutter shaft 125 is guided ina framework comprising radial spokes 123 fixed to the duct 114 and acentral sleeve 124.

Considering now the aspects of this embodiment affected by the instantinvention, the duct 114 carries a differential gear unit 126 which issupported by its two input shafts 127 and 128 (which correspond to theshafts 39 and 47, respectively, in Figure 3). Shaft 127 is fast on theinner shell, and the ring 117 and duct 114 are rotatable about thisshaft, whereby it serves to center the duct with respect to the matrixdrum. A fluid-tight running seal is provided at 129. The shaft 128 isrotatably mounted on an open spider 130 carried by the duct 114; it isrotated at angular velocity proportional to the angular velocity of theshutter 120 through spur gears 131 and 132, shaft 133, sprocket 134,sprocket chain 135 and sprocket 136, the last being fast on the shuttershaft 125. The shaft 133 that carries the gear 132 and sprocket 134 isrotatably mounted in the spider 130 and in a bracket 137 projecting fromthe duct 114. The shutter shaft 125 terminates within a sleeve 138 andhas axial and rotary motion relative thereto, but is guided thereby toposition the axis of the shutter shaft. Axial thrust is trans mittedfrom the sleeve to the shaft by a thrust bearing 139 carried by thesleeve and a spring 140 acting between the rotatable race of the bearingand a collar on the shutter shaft. The sleeve 138 is internally threadedand receives a threaded stud 141 that is stationary with respect to theduct 114, whereby rotation of the sleeve moves the thrust bearing towardor away from the shutter to vary the loading on the spring 140 and theshutter. The sleeve 138 has a peripheral sprocket 142 fixed thereto,connected by a sprocket chain 143 to a sprocket 144 which is infrictional engagement with the housing of the differential gear unit,replacing the lever 50 of Figure 3.

When the embodiment of Figure is in operation, power is applied to thespur gear 119, thereby rotating the ring 117 and the rotatable duct 114at a positivelyinduced angular velocity about the stationary matrix drum110 and the stationary shaft 127. Frictional forces cause the shutter120 to rotate at a frictionally-induced angular velocity. Considered inrelation to the duct 114, the input shafts 127 and 128 of thedifferential gear unit 126 are turned in opposite directions and atvelocities proportional to the positively-induced andfrictionallyinduced velocities, respectively, the proportionality beingdependent upon the relative sizes of the gears 131 and 132 and thesprockets 134 and 136, which are selected to cause the casing of thedifferential gear unit to remain stationary with respect to the duct 114when the induced velocity ratio is at a desired, predetermined value,preferably close to the aforesaid critical value. Should the angularveloc ity of the shutter 12!) be too low, indicating too high an inducedvelocity ratio, the casing of the differential gear unit rotates toplace a torque on the sprocket 144 which rotates to turn the sleeve 138on the threaded stud 141; this increases the loading on the spring 140and, hence, on the shutter 120, thereby lowering the induced velocityratio. Conversely, when the shutter is pressed against the matrix drumtoo tightly the induced velocity ratio is too low, and the differentialgear casing causes the sleeve 138 to rotate in the opposite direction,thereby decreasing the loading and increasing the induced velocityratio.

I claim as my invention:

1. A regenerative heat exchanger comprising three members of which oneis a heat accumulating matrix having separate matr'nt ducts terminatingin an end contact face, the second is a shutter support situatedopposite to and eccentric to said contact face and the third is ashutter mounted on said support and having a peripheral sealing face insealing and rubbing engagement with said contact face over a minor,eccentric portion of the area of the contact face and having further aflow opening within said peripheral sealing face, said support andmatrix being relatively rotatable for causing the shutter to sweep thecontact face with a sweeping rotary movement about the center of thecontact face and said shutter being mounted to have a rotary movementrelative to the matrix separate from said sweeping movement about anaxis that is eccentric to the center of the contact face; first andsecond conduits disposed for the flow of different heat exchange media,one of said conduits being in flow communication with said flow openingin the shutter and the other being in flow communication with thetermini of matrix ducts that lie outside of said shutter; means for apressure between said shutter and the contact face of the matrix; andmeans for varying the said pressure during the said rotary movements.

2. A regenerative heat exchanger according to claim 1 wherein said meansfor positively rotating one of the three members comprises a drive shaftconnected to the shutter ring for positively rotating the shutter ring.

3. A regenerative heat exchanger according to claim 1 wherein saidmatrix is a rotatable drum and the means for positively rotating one ofthe three members comprises a drive pinion cooperating with the matrixdrum for positively rotating the matrix drum.

4. A regenerative heat exchanger having a heat accumulating matrix drumwith a plurality of separate, longitudinal matrix ducts terminating inend contact faces; a first pair of conduits for the flow of a first heatexchanging medium situated at opposite ends of the drum and having portsadjacent said faces and eccentric thereto; a shutter for each of saidports, each shutter having a peripheral sealing face in sealing andrubbing engagement with the respective contact face and surrounding aminor, eccentric portion of the area of said contact face, said shutterhaving a flow opening inside of the peripheral sealing facecommunicating with the respective first condui-t and being mounted forrotation relative to the drum and relative to the first conduits aboutan axis eccentric to the central axis of the drum; a shutter support foreach shutter mounted for relative sweeping movement of the supportedshutters over the matrix contact faces; means for effective positivemovement of one of said relatively movable elements, thereby inducingthe other of said movements; second conduit means at opposite ends ofsaid drum communicating with the termini of matrix ducts that lieoutside of the shutters for the flow of a second heat exchanging medium;means for applying a pressure between the shutters and the said contactfaces; and means for varying said pressure during said movements.

5. A regenerative heat exchanger comprising three members of which oneis a heat accumulating matrix having separate matrix ducts terminatingin an end contact face, the second is a shutter support situatedopposite to and eccentric to said contact face and the third is ashutter mounted on said support and having a peripheral sealing face insealing and rubbing engagement with said contact face over a minor,eccentric portion of the area of the contact face and having further aflow opening within said peripheral sealing face, said support andmatrix being relatively rotatable for causing the shutter to sweep thecontact face with a sweeping rotary movement about the center of thecontact face and said shutter being mounted to have a rotary movementrelative to the matrix separate from said sweeping movement about anaxis that is eccentric to the center of the contact face; first andsecond conduits disposed for the how of different heat exchange media,one of said conduits being in flow communication with said flow openingin the shutter and the other being in flow communication with thetermini of matrix ducts that lie outside of said shutter; means forpositively rotating one of said three members to induce positively oneof said rotary movements, thereby inducing the other of said rotarymovements b'y friction between said contact face and the sealing face; asensing device for sensing the relation between the velocities of saidrotary movements; and a variable pressure device responsive to saidsensing device for applying an increased pressure between said shutterand the contact face of the matrix when the velocity of the positivelyinduced rotary movement increases in relation to the velocity of thefrictionally induced rotary movement.

6. A regenerative heat exchanger according to claim wherein said sensingdevice comprises a differential speed device having one input connectedto move in accordance with the said rotary movement of the shutter aboutthe eccentric axis and a second input connected to move in accordancewith the rotary sweep movement and having the output thereof connectedto control said variable pressure device.

7. A regenerative heat exchanger according to claim 6 wherein thevariable pressure device comprises a servomechanism operating inresponse to the said output of the differential speed device to increasethe said pressure.

8. A regenerative heat exchanger according to claim 5 wherein saidmatrix is rotatable to effect said sweeping movement; said sensingdevice comprises a differential gear unit of which one input isdrivingly connected to the rotating shutter and another input isdrivingly connected to the matrix; and the variable pressure devicecomprises a hydraulic piston and cylinder combination arranged to applya loading on the shutter when hydraulic fluid under pressure is admittedto the cylinder, a source of hydraulic fluid under pressure, and apressure regulating valve connected between the said source and thecylinder, said valve being connected to be controlled by the output ofsaid differential gear unit.

9. A regenerative heat exchanger according to claim 5 wherein theshutter support comprises a rotatable and axially movable shaftconnected in axial thrustand torque-transmitting relation to the shutterand the variable pressure device is connected to said shaft forimparting axial thrust thereto. 10. A regenerative heat exchangeraccording to claim 9 wherein the said means for positively rotating oneof the three members comprises drive means acting on said shaft forrotating the shaft and shutter.

ll. A regenerative heat exchanger according to claim 9 wherein thematrix is rotatable and the said means for positively rotating one ofthe three members comprises a drive pinion cooperating with said matrixfor positively rotating the matrix. 7

12. A regenerative heat exchanger according to claim 5 wherein thematrix is rotatable and the sensing device has one input thereofdrivingly connected to the matrix by a friction wheel in engagement withthe periphery of the matrix.

13. A regenerative heat exchanger according to claim 5 wherein thematrix is stationary and the shutter support is mounted for rotationabout the center of the matrix contact face; the said means forpositively rotating one of the three members comprises drive meansacting on the shutter support to effect the said sweeping rotarymovement, whereby rotation of the shutter on the shutter support aboutthe eccentric axis thereof is induced by friction.

14. A regenerative heat exchanger according to claim 13 wherein thesensing device comprises a differentialgear unit mounted for rotationbodily with the said shutter support, one input of said gear unit beingdrivingly connected to a stationary part of the heat exchanger andanother input thereof being drivingly connected to the shutter supportedby the shutter support.

. 15. A regenerative heat exchanger having a heat respect to the saidconduits for rotary movements about 7 12 accumulating matrix drum with aplurality of separate, longitudinal matrix ducts terminating in endcontact faces; a first pair of conduits for the flow of a first heatexchanging medium. situated at opposite ends of the drum and havingports situated adjacent said facesand eccentric to the central axis ofthe drum, a ring-shaped shutter at each port communicating therewith andadapted formotion in a direction parallel to said central axis of thedrum, said shutter having a peripheral sealing face in sealing andrubbing engagement with the respective contact face and surrounding aminor, eccentric portion of the area of said contact face, said drum andport being relatively rotatable. about the central axis of the matrixdrum to cause said shutters to sweep said end Contact faces with arotary sweeping movement, said shutters being rotatable with axeseccentric to said central axis of the drum separate from said sweepingmovement; second conduits at oppo-' site ends of said drum communicatingwith the termini of matrix ducts that lie outside of the shutters forthe flow of a second heat exchanging medium; drive means for positivelyinducing one of said rotary movements, whereby the other of said rotarymovements is induced by friction between said contact faces and saidshutters; a differential speed sensing unit connected to sense theinduced velocity ratio; a variable pressure device for applying avariable pressure on the shutters urging them against the contact facesof the drum; and control means for the variable pressure deviceresponsive to the output of the dilfcrential speed sensing unit forincreasing the pressure when the induced velocity ratio rises above apredetermined value and for decreasing the said pressure when theinduced velocity ratio falls below said predetermined va ue.

16. A regenerative heat exchanger of the kind specified having a heataccumulating matrix drum with a plurality of separate, longitudinalmatrix ducts terminating'in end contact faces and mounted for rotationabout the central axis thereof; first conduits for the flow of one heatexchanging medium situated at opposite ends of the drum and havingstationary ports adjacent said faces, said ports covering minor portionsof said end faces and being eccentric to said central axis; aring-shaped shutter at each of said ports mounted in sealing relationthereto and being rotatable about an axis eccentric to said centralaxis, each shutter having a sealing face disposed in sealing and rubbingengagement with the respective end contact face; a pair of secondconduits for the flow of a second heatexchanging medium, one conduitbeing connected to each face of the drum for communication with theterminiof matrixducts lying outside of said shutters; and a shaft for atleast one of said shutters connected in torquetransmitting relation tothe shutter and extending rotativel y through awall of. a first conduitfor rotation with said shutter.

17. A regenerative heat exchanger according to claim 16 wherein saidshaft is connected also in axial thrusttransmitting relation to saidshutter and the shutter is mounted for axial movement toward and fromsaid matrix drum, said shaft having connected, thereto a variablepressure device for applying an axial thrust to the shaft in a directiontoward the matrix drum.

18. In combination with the heat exchanger according to claim 17, meansfor positively rotating one of said rotatable members; means for sensingthe induced velocity ratio; and control. means responsive to the sensedinduced. velocity ratio for increasing said thrust applied to the shaftas the sensed induced velocity ratio increases,

